Anthrax toxin-mediated delivery in vivo and in vitro of a cytotoxic T-lymphocyte epitope from ovalbumin.
We reported earlier that a nontoxic form of anthrax toxin was capable of delivering a cytotoxic T-lymphocyte (CTL) epitope in vivo, such that a specific CTL response was primed against the epitope. The epitope, of bacterial origin, was fused to an N-terminal fragment (LFn) from the lethal-factor component of the toxin, and the fusion protein was injected, together with the protective antigen (PA) component, into BALB/c mice. Here we report that PA plus LFn is capable of delivering a different epitope--OVA(257-264) from ovalbumin. Delivery was accomplished in a different mouse haplotype, H-2Kb and occurred in vitro as well as in vivo. An OVA(257-264)-specific CTL clone, GA-4, recognized EL-4 cells treated in vitro with PA plus as little as 30 fmol of the LFn-OVA(257-264) fusion protein. PA mutants attenuated in toxin self-assembly or translocation were inactive, implying that the role of PA in epitope delivery is the same as that in toxin action. Also, we showed that OVA(257-264)-specific CTL could be induced to proliferate by incubation with splenocytes treated with PA plus LFn-OVA(257-264). These findings imply that PA-LFn may serve as a general delivery vehicle for CTL epitopes in vivo and as a safe, efficient tool for the ex vivo expansion of patient-derived CTL for use in adoptive immunotherapy.
Ballard
J D
JD
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Doling
A M
AM
Beauregard
K
K
Collier
R J
RJ
Starnbach
M N
MN
D000818:Animals; D000942:Antigens, Bacterial; D001427:Bacterial Toxins / Q000008:administration & dosage*; D018984:Epitopes, T-Lymphocyte; D005260:Female; D016219:Immunotherapy, Adoptive; D051379:Mice; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D018984:Epitopes, T-Lymphocyte; D010446:Peptide Fragments; C030325:anthrax toxin; D010047:Ovalbumin